Rare germline deleterious variants increase susceptibility for lung cancer

Pathogenic germline variants in BRCA1 and TP53 increase lung cancer risk in Chinese

BACKGROUD

Multiple studies have identified pathogenic germline variants in cancer susceptibility genes (CSGs) in Chinese lung cancer patients; however, accurate assessment of these variants' contributions to cancer predisposition is always hampered by the absence of data on the prevalence of these variants in the general population. It is necessary to conduct a large-scale case-control study to identify CSGs that significantly increase the risk of lung cancer.

MATERIALS AND METHODS

We performed targeted sequencing of a CSGs panel in 1117 lung cancer patients and 16,327 controls from the general Chinese population.

RESULTS

In comparison to controls, lung cancer patients had a considerably higher prevalence of pathogenic and likely pathogenic (P/LP) variations. Among lung cancer patients, 72% of P/LP variants carriers did not have a family cancer history, who would be ignored if germline testing was only provided for patients meeting family history-based criteria. Furthermore, compared to individuals with late-onset lung cancer, patients with early-onset lung cancer had a considerably higher prevalence of P/LP variations. With odds ratios (ORs) ranging from 4-fold (BRCA1: OR, 4.193; 95%CI, 1.382-10.768) to 29-fold (TP53: OR, 29.281; 95%CI, 1.523-1705.506), P/LP variants in the BRCA1 and TP53 genes were discovered to be strongly related to increased lung cancer risk. Additionally, with ORs ranging from 7.322-fold to infinity, we discovered 23 variations previously categorized as non-P/LP variants were highly enriched in lung cancer patients.

CONCLUSION

Our findings indicated that P/LP variants in BRCA1 and TP53 conferred increased risk of lung cancer in Chinese.

Somatic and germline ATM variants in non-small-cell lung cancer: Therapeutic implications

ATM is an apical kinase of the DNA damage response involved in the repair of DNA double-strand breaks. Germline ATM variants (gATM) have been associated with an increased risk of developing lung adenocarcinoma (LUAD), and approximately 9% of LUAD tumors harbor somatic ATM mutations (sATM). Biallelic carriers of pathogenic gATM exhibit a plethora of immunological abnormalities, but few studies have evaluated the contribution of immune dysfunction to lung cancer susceptibility. Indeed, little is known about the clinicopathological characteristics of lung cancer patients with sATM or gATM alterations. The introduction of targeted therapies and immunotherapies, and the increasing number of clinical trials evaluating treatment combinations, warrants a careful reexamination of the benefits and harms that different therapeutic approaches have had in lung cancer patients with sATM or gATM. This review will discuss the role of ATM in the pathogenesis of lung cancer, highlighting potential therapeutic approaches to manage ATM-deficient lung cancers.

Germline EGFR c.2527G > A (p.V843I) variant and familial lung cancer

BACKGROUND

Somatic epidermal growth factor receptor (EGFR) pathogenic variants have been identified and are routinely tested in the molecular diagnosis of non-small cell lung cancer (NSCLC) as they represent a target for EGFR tyrosine kinase inhibitor (TKI) therapy. However, germline variants in EGFR are much less frequently reported.

CASE PRESENTATION

Herein, we report the case of a 46-year-old woman diagnosed with lung adenocarcinoma who was found to harbor a rare germline missense variant in exon 21 of EGFR: NM_005228.5(EGFR):c.2527G>A (p.V843I). In the tumor, this variant (Cosmic ID COSV51767379) was accompanied by a secondary, known pathogenic EGFR variant in cis, also occurring in exon 21, c.2573T>G (p.L858R) (Cosmic ID 6224). Her mother was previously diagnosed with poorly differentiated lung carcinoma and her tumor was also found to harbour the p.V843I variant but no other pathogenic variants. Notably, the proband's sister, diagnosed with a lung carcinoma with sarcomatous features at age 44, did not carry this variant or any other somatic or germline EGFR variants.

CONCLUSION

This is the second report of familial lung adenocarcinoma associated with the germline p.V843I variant, which remains classified as a variant of uncertain significance. The lack of segregation of this variant in the proband's affected sister illustrates the complexity with evaluating lung cancer predisposition factors. Currently, there is a paucity of data regarding the therapeutic outcomes of patients with tumors expressing this rare germline variant, therefore we propose an algorithm for the identification of at-risk individuals and families as the first step for their personalized management.

Atypical ATMs: Broadening the phenotypic spectrum of ATM-associated hereditary cancer

Heterozygous, loss-of-function germline variants in ATM have been associated with an increased lifetime risk of breast, pancreas, prostate, stomach, ovarian, colorectal, and melanoma cancers. We conducted a retrospective review of thirty-one unrelated patients found to be heterozygous for a germline pathogenic variant in ATM and identified a significant proportion of patients in this cohort with cancers not currently associated with the ATM hereditary cancer syndrome, including carcinomas of the gallbladder, uterus, duodenum, kidney, and lung as well as a vascular sarcoma. A comprehensive review of the literature found 25 relevant studies where 171 individuals with a germline deleterious ATM variant have been diagnosed with the same or similar cancers. The combined data from these studies were then used to estimate the prevalence of germline ATM pathogenic variants in these cancers, which ranged between 0.45% and 2.2%. Analysis of tumor sequencing performed in large cohorts demonstrated that the frequency of deleterious somatic ATM alterations in these atypical cancers equaled or exceeded the alteration frequency in breast cancer and occurred at a significantly higher rate than in other DNA-damage response tumor suppressors, namely BRCA1 and CHEK2. Furthermore, multi-gene analysis of somatic alterations in these atypical cancers demonstrated significant co-occurrence of pathogenic alterations in ATM with BRCA1 and CHEK2, while there was significant mutual exclusivity between pathogenic alterations in ATM and TP53. This indicates that germline ATM pathogenic variants may play a role in cancer initiation and progression in these atypical ATM malignancies, potentially influencing these cancers to be driven toward DNA-damage repair deficiency and away from loss of TP53. As such, these findings provide evidence for broadening of the ATM-cancer susceptibility syndrome phenotype to improve the recognition of affected patients and provide more efficacious, germline-directed therapies.

Characterization of lung cancers in patients with BRCA germline variants: A multicenter series

INTRODUCTION

BRCA1 and BRCA2 (BReast CAncer susceptibility genes) are two tumor-suppressor genes associated with the hereditary breast and ovarian cancer susceptibility syndrome. Recent studies also suggest an increased lung adenocarcinoma risk in carriers.

METHODS

We conducted a multi-center retrospective study in 18 different French pulmonology and/or oncology departments on medico-administrative and clinical data prospectively collected in the Clinical Data Warehouse (CDW) of Greater Paris University Hospitals (Assistance Publique-Hôpitaux de Paris, AP-HP). Clinical characteristics and outcomes of patients with LC and a previously known BRCA1/2gl variant were retrospectively evaluated.

RESULTS

17 patients with LC and known BRCA1/2gl variant were included. Patients were most women, former smokers with localized disease and BRCA2 variants. All LC were adenocarcinoma. For patients with medical history of cancer, median time from the first cancer in the BRCA spectrum and the LC occurrence was 20 years. Median disease-free survival (DFS) and overall survival (OS) in localized tumor (Stage I and II) was not reached and 78.6 months, respectively. In advanced cancer (Stade III and IV) median progression free survival was 9.7 months and median OS was 17.8 months. Univariate OS and DFS/PFS analyses by BRCA status did not find significant differences.

CONCLUSION

Results seem to show particular LC features in carriers of BRCA2 variants: adenocarcinoma subtype, woman, former or non-smoker.